Zhang is well-known amongst elite circles in China for her wealth, a result of her own business dealings in the diamond trade. Barboza says that she is now known as China's "diamond queen".

Zhang worked as a regulator for China's Ministry of Geology, helping to set the standards for the nascent industry. As her husband worked his way through the ranks, she began to blur the line between regulator and businesswomen. She used state money to help set up Beijing Diamond, a big jewelry retailer, and later set up Sino-Diamond, a venture financed by the state-owned China Mineral and Gem Corporation (of which she was the boss).

She later used the profits from the diamond industry to move into other ventures, always being careful to remain in the background of business dealings.

Barboza states that he didn't find any instances of Wen explicitly using his power to help his wife — but people bent over backwards to help her anyway, without his interjections.

“Her business activities are known to everyone in the leadership,” one banker told Barboza, and added it was not unusual for her to directly call people in the business world. “And if you get that call, how can you say no?”

Wen wasn't unaware of this. According to a WikiLeaks release of one US State Department cable, Wen was "disgusted by his family's activities. Wen's wife and children all have a reputation as people who can 'get things done' at the right price." The Chinese premier was considering a divorce, according to the cable.